Comparative Morphological, Histometric and Histochemical studies of Parotid and Mandibular Salivary Glands of Camel, Ox, Sheep and Goat

Abstract

This study was performed on 100 heads of adult healthy camels, ox, sheep and goats (25 heads for each animal). Gross anatomical, histological, histometric, histochemical and ultrastructural studies were carried out on the parotid and mandibular salivary glands of the animals mentioned above. The samples were obtained from Alssalam slaughter house in Omdurman, Sudan during the period (April 2013-April 2014). The aim of this investigation was to compare the morphology and histochemistry of the parotid and mandibular salivary glands in camels, oxen, sheep and goats. The anatomical studies demonstrated that the parotid gland was partially covered by parotidoauricularis muscle in camel, completely covered in ox but only superficial in sheep and goat. It was irregularly rectanglular in camel and ox, irregularly-shaped in sheep and triangular in goat. There was a variation in the weight, length, width and thickness of the gland among these animals. The parotid duct left the gland from the medial surface and crossed the lateral surface of the masseter muscle to open at a mucosal papilla opposite to the second molar tooth in camel, sheep and goat and opposite to the fifth upper tooth in the ox. The mandibular gland was irregularly rectangular in camel, elongated in ox and irregularly-shaped in sheep and goat. The mandibular duct passed between the digastricus and ventral to the pterygoideus muscle, along the lower jaw between the mylohyoideus and geniohyoideus muscles to the external surface of the styloglosuss muscle in camel and ox. In sheep and goat the duct passed between the omohyoideus, mylohyoideus and geniohyoideus muscles beside the styloglosuss muscle. It opened in the oral cavity at a mucosal fold in camel and at the sublingual caruncle in the ox, sheep and goat. The histological findings showed that both the parotid and mandibular glands were compoundtubulo-acinar in camel, ox and sheep and were compoundtubulo-alveolar in goat. The secretory units of parotid gland were mixed; serous and mucus in camel and purely serous in ox, sheep and goat. The mandibular gland was seromucous in all animals used. In addition; the demilunes which capped the mucous acini were serous in camel, ox, sheep and goat. The parenchyma of the parotid and mandibular glands had three types of acini of different morpholoigal and histometric features. The duct system of parotid and mandibular glands consisted of intercalated, striated, intralobular and interlobar ducts which varied in shape and location. Myoepithelial cells were located in the angles between two cells of acini and between cells of the intercalated duct of parotid and mandibular glands. The histometric measurements revealed three types of acini and four types of ducts. A significant difference (P˂0.05) was recorded between small, intermediate and large acini and intercalated, striated, interlobular and interlobar ducts in camel, ox, sheep and goat. The ultrstrucural studies of parotid and mandibular glands demonstrated the presence of numerous mitochondria, secretory granules and rough endoplasmic reticulum in the cytoplasm in camel, ox, sheep and goat. In both parotid and mandibular glands the mitochondria were well developped in the gland of ox, camel, goat and sheep. The gland of sheep was characterized by abundant secretory granules. The nucleus in both parotid and mandibular glands had clear chromatin granules and the nuclear membrane was more folded in ox, goat, sheep and camel. The histochemical observation showed a difference in the degree of PAS-positive reaction in the acini of the parotid and mandibular glands of camel, ox, sheep and goat. AB reaction used AB/PAS sequence reactions were negative in parotid gland and were positive in the mandibular gland of camel, ox, sheep and goat.